Helleborus plant named ‘COSEH 820’

ABSTRACT

A new and distinct cultivar of  Helleborus  plant named ‘COSEH 820’, characterized by its upright and uniformly mounded plant habit; uniform and freely flowering habit; dark green-colored leaves; long flowering period; single light yellow green and white-colored flowers; and good garden performance.

Botanical designation: Helleborus niger×Helleborus argutifolius.

Cultivar denomination: ‘COSEH 820’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar of Helleborus plant, botanically known as Helleborus niger×Helleborus argutifolius, and hereinafter referred to by the name ‘COSEH 820’.

The new Helleborus plant is a product of a planned breeding program in Glandorf, Germany. The objective of the breeding program was to create new uniform Helleborus plants with unique and attractive plant habit, leaf and flower coloration and resistance to pests.

The new Helleborus plant originated from a cross-pollination conducted by the Inventor in Glandorf, Germany in November, 2003 of an unnamed proprietary seedling selection of Helleborus niger, not patented, as the female, or seed, parent with an unnamed proprietary seedling selection of Helleborus argutifolius, not patented, as the male, or pollen, parent. The new Helleborus plant was discovered and selected by the Inventor as a single flowering plant from within the progeny of the stated cross-pollination grown in a controlled greenhouse environment in Glandorf, Germany in February, 2006.

Asexual reproduction of the new Helleborus plant by divisions in a controlled greenhouse environment in Glandorf, Germany since March, 2006, has shown that the unique features of this new Helleborus plant are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

Plants of the new Helleborus have not been observed under all possible environmental conditions and cultural practices. The phenotype may vary somewhat with variations in environmental conditions such as temperature and light intensity without, however, any variance in genotype.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘COSEH 820’. These characteristics in combination distinguish ‘COSEH 820’ as a new and distinct Helleborus plant:

-   -   1. Upright and uniformly mounded plant habit.     -   2. Uniform and freely flowering habit.     -   3. Dark green-colored leaves.     -   4. Long flowering period.     -   5. Single light yellow green and white-colored flowers.     -   6. Good garden performance.

Compared to plants of the parent selections, plants of the new Helleborus are more uniformly mounded and are more uniformly and freely flowering.

Plants of the new Helleborus can be compared to plants of Helleborus niger×Helleborus lividus ‘COSEH 700’, disclosed in U.S. Plant Pat. No. 21,003. In side-by-side comparisons conducted in Glandorf, Germany, plants of the new Helleborus differed primarily from plants of ‘COSEH 700’ in leaf color as plants of the new Helleborus had lighter green-colored leaves than plants of ‘COSEH 700’. In addition, plants of the new Helleborus and ‘COSEH 700’ differed slightly in flower color.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying colored photographs illustrate the overall appearance of the new Helleborus plant showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Colors in the photographs may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Helleborus plant.

The photograph on the first sheet comprises a side perspective view of a typical flowering plant of ‘COSEH 820’ grown in a container.

The photograph on the second sheet is a close-up view of a typical flowering plant of ‘COSEH 820’.

DETAILED BOTANICAL DESCRIPTION

The aforementioned photographs and following observations, measurements and values describe plants grown in 15-cm containers during the winter in a glass-covered greenhouse in Glandorf, Germany and under conditions which closely approximate commercial Helleborus production. During the production of the plants, day temperatures ranged from 12° C. to 32° C. and night temperatures ranged from 3° C. to 18° C. Plants were 14 months old when the photographs and the description were taken. In the following description, color references are made to The Royal Horticultural Society Colour Chart, 2007 Edition, except where general terms of ordinary dictionary significance are used.

-   Botanical classification: Helleborus niger×Helleborus argutifolius     ‘COSEH 820’. -   Parentage:     -   -   Female, or seed, parent.—Unnamed proprietary seedling             selection of Helleborus niger, not patented.         -   Male, or pollen, parent.—Unnamed proprietary seedling             selection of Helleborus argutifolius, not patented. -   Propagation:     -   -   Type.—By tissue culture.         -   Time to initiate roots.—About two months at 12° C.         -   Time to produce a rooted young plant.—About six months at             4° C. to 15° C.         -   Root description.—Thick to thin, fleshy; white to brown in             color.         -   Rooting habit.—Sparse. -   Plant description:     -   -   Plant form and growth habit.—Herbaceous perennial; upright             and uniformly mounding plant habit with flowers held just             above the foliar plane; plant shape is globular; and             moderately vigorous growth habit.         -   Plant height—About 28.7 cm.         -   Plant diameter (area of spread).—About 31.3 cm. -   Foliage description:     -   -   Arrangement.—Leaves arranged in a basal rosette; leaves             palmately compound with five leaflets per leaf.         -   Leaf length.—About 15.2 cm.         -   Leaf width.—About 17.9 cm.         -   Leaflet length.—About 10.4 cm.         -   Leaflet width.—About 4.8 cm.         -   Leaf shape.—Palmate; orbicular in outline.         -   Leaflet shape.—Elliptic to broadly ovate.         -   Leaflet apex.—Acute.         -   Leaflet base.—Attenuate.         -   Leaflet margin.—Sharply serrate.         -   Leaflet texture, upper and lower surfaces.—Smooth, glabrous;             leathery.         -   Leaflet venation pattern.—Pinnate.         -   Leaflet color.—Developing leaves, upper surface: Close to             137A. Developing leaves, lower surface: Close to 146B. Fully             developed leaves, upper surface: Between N137A and 147A;             venation, close to 144A to 144B. Fully developed leaves,             lower surface: Close to 147B; venation, close to 144B to             144C.         -   Petiole.—Length: About 6.7 cm. Diameter: About 5 mm.             Texture, upper and lower surfaces: Smooth, glabrous. Color,             upper and lower surfaces: Close to 144C. -   Flower description:     -   -   Flower shape and habit.—Single rotate flowers arranged in             terminal and axillary cymes; freely and uniform flowering             habit with about 75 flowers and flower buds per plant;             flowers facing outwardly to slightly nodding and slightly             upright.         -   Fragrance.—None detected.         -   Natural flowering season.—Plants begin flowering about ten             months after planting; long flowering period; plants flower             from late winter to early spring in Germany.         -   Flower longevity on the plant.—About ten days; flowers not             persistent.         -   Flower buds.—Length: About 1.9 cm. Diameter: About 1.1 cm.             Shape: Ovate. Color: Close to 145C.         -   Inflorescence height.—About 24.2 cm.         -   Inflorescence diameter.—About 22.9 cm.         -   Flower diameter.—About 6.6 cm.         -   Flower depth (height).—About 2.4 cm.         -   Petals.—Transformed into nectaries.         -   Sepals.—Quantity and arrangement: Five arranged in a single             whorl. Length: About 3.5 cm. Width: About 2.6 cm. Shape:             Broadly ovate to broadly elliptic. Apex: Rounded. Margin:             Entire. Texture, upper and lower surfaces: Smooth, glabrous.             Color: When opening, upper surface: Close to 145B; towards             the margins, close to 145C. When opening, lower surface:             Close to 145C. Fully opened, upper surface: Close to 145C to             145D; towards the margins, close to NN155A; towards the             base, close to 145B; with development, color becoming closer             to 144C. Fully opened, lower surface: Close to 145C; towards             the base, close to 145A to 145B.         -   Peduncles.—Strength: Moderately strong. Length: About             13.5 cm. Diameter: About 7 mm. Aspect: About 10° from             vertical. Texture: Smooth, glabrous. Color: Close to 145B to             145C heavily dotted with close to 182B.         -   Pedicels.—Strength: Moderately strong. Length: About 2.7 cm.             Diameter: About 2 mm. Aspect: Erect to about 30° from the             peduncle axis. Texture: Smooth, glabrous. Color: Close to             145A.         -   Reproductive organs.—Stamens: Quantity per flower: About 60.             Filament length: About 1.5 cm. Filament color: Close to             157D. Anther shape: Reniform. Anther length: About 2 mm.             Anther color: Close to 150B. Pollen amount: Scarce. Pollen             color: Close to 158D. Pistils: Quantity per flower: About             five. Pistil length: About 1.1 cm. Stigma shape:             Club-shaped. Stigma color: Close to 150D. Style length:             About 9 mm. Style color: Close to 150D. Ovary color: Close             to 145B to 145C. Nectaries (transformed petals): Quantity             per flower: About 14. Length: About 8 mm. Diameter, apex:             About 2 mm. Diameter, base: About 1 mm. Shape: Flattened             triangular. Color: Close to 144B to 144C; towards the apex,             close to N144A.         -   Seeds/fruits.—Seed and fruit development have not been             observed. -   Garden performance: Plants of the new Helleborus have been observed     to have good garden performance and to tolerate rain and wind.     Plants of the new Helleborus have been observed to tolerate high     temperatures of about 35° C. and are hardy to USDA Hardiness Zone 5. -   Pathogen/pest resistance: Plants of the new Helleborus have not been     shown to be resistant to pathogens and pests common to Helleborus. 

1. A new and distinct Helleborus plant named ‘COSEH 820’ as illustrated and described. 